Installing OS X or MacOS from old disk image files

What a pain in the tail. You tried to install Ubuntu on an old Mac Mini, then found that it really does not work well with all the devices (wireless) etc in the box. So you try to reinstall OS X on the machine. Well after you figure out how to make the install disks via the ‘createinstallmedia’ command

Inside the installXXX.app you will find in the Contents/Resources/ folder an application called createinstallmedia. This will make a USB drive into an install disk:

Now comes the annoying part: Every time you create a disk, when you try to use it to reinstall the OS from the USB, that you just booted from because you know how to install the OS from the Recovery prompt….. you get the following “This copy of the Install OS X El Capitan application can’t be verified. It may have been corrupted or tampered with during downloading.”

What I ended up having to do it roll back the system date on the computer. To do this just open up the terminal from the command prompt and change the date with the date command (use a date that was not too far from the original date the OS was released).